Hey, It seems to me like you were supposed to do something else before entering that command? likely deactivate some other process or similar as conflicts will cause processes to get killed. You can run a command (check kill) that will highlight and kill any conflicting processes, I assume it will be possible on the ipod too?
The thing is though, are you aware of what you are actually doing here? by that I mean do you know what the command you are entering means? are you trying to open packets that you have previously captured on your computer or whatever? because you cannot put the ipod wireless card into monitor mode (as far as I know) so aircrack isn't the most useful thing to have on there. I am open to correction on this, I only looked into it very briefly when I had an iphone, if anyone else knows better, holla.
I would suggest playing around with aircrack on your computer if you don't already, and getting familiar with the commands because, going by your comment, I don't think that this will do what you expect.
edit: you may find this link interesting: http://aircrack-ng.blogspot.co.uk/2012/ ... phone.html
edit (again): I see whats going down, you're following something like this aren't you? http://www.youtube.com/watch?v=C_6is7YQbr4
Read the comments in that vid, point 4 may help you with your problem. Also note the little disclaimer:
"NOTE: This DOESN'T work FULLY yet. All this is doing is cracking a sample file supplied with it but can not crack a wifi network on its own yet."
ties in nicely with what the official blog says eh?
My apologies if you already knew that and were just following along for kicks, but I thought I would point it out in case you were expecting something more. Have fun.
A wise man can learn more from a foolish question than a fool can learn from a wise answer.